1. Field of the Invention
The present invention relates to a sheet material feeding device for feeding a sheet material (a recording paper, a transfer paper, a photosensitive paper, an electrostatic recording paper, a printing paper, an OHP sheet, an envelope, a postcard, a sheet document, or the like) mounted on a sheet material mounting portion to a sheet material processing portion such as a recording portion, a reading portion, and a processing portion in a recording apparatus (printer) as an information outputting apparatus for a personal computer, or the like, an image forming apparatus such as a copying machine and a facsimile, or various other kinds of sheet material using appliances, and a recording apparatus comprising the sheet material feeding device.
2. Related Background Art
According to a sheet material feeding device for sending out sheet materials mounted on a sheet mounting portion, a function of certainly separating and feeding (sending out) the mounted sheet materials one by one. For example, Japanese Patent Application Laid-Open No. 2-193834 discloses a sheet material feeding device required to separate various sheet materials with different bending elastic modules provided with the function. According to this, in a sheet material feeding device for sending out the sheet materials by forcing a sheet material mounting base with sheet materials forced toward a feeding roller with a spring, and rotating the feeding roller, an elastic member is disposed in a direction perpendicular to the sheet material feeding direction so that the sheet materials are separated one by one by deflecting the elastic member.
However, according to the sheet material feeding device, since the sheet material mounting base is always forced toward the feeding roller, in the case not only the uppermost sheet material but also subsequent sheet materials are pushed out, the top end portion of the subsequent sheet materials may be abutted against the elastic member so as to be interposed and maintained between the sheet material mounting base and the feeding roller in a state with the elastic member deflected. In the case a feeding operation is further executed for the subsequent sheets, a sufficient separating effect by the elastic member cannot be obtained so that the superimposed feed of the sheet materials (feed with a plurality of sheets superimposed) may be generated.
As means for solving the problem, for example, Japanese Patent Application Laid-Open No. 8-40589 discloses one comprising means for releasing the pressure contact force between the sheet material mounting base and the feeding roller after separating and feeding the first sheet material to the device main body. According to the means, since the elastic member in the deflected state can return to the original state by its own elastic returning force, the subsequent sheet materials are pushed back to the initial mounting position so that generation of the superimposed feed of the subsequent sheet materials at the time of the feeding operation can be avoided.
However, according to the conventional sheet material feeding device comprising the means for releasing the pressure contact force between the sheet material mounting base and the feeding roller has the following technical problem to be solved. That is, although the pressure contact force between the sheet material mounting base and the feeding roller is released after separating the first sheet material and feeding the same to the device main body, since the force of returning the elastic member in the deflected state to the original state is only the own elastic force of the elastic member, in the case a load exists in the process of returning the subsequent sheet materials to the initial state, a risk is involved in that the sheet materials cannot be pushed back completely. Moreover, even in the case the elastic member returns to the original state, the subsequent sheet materials is maintained in a state hooked by the elastic member without completely returning to the initial mounting position. Therefore, a risk is involved in that a sufficient separating effect by the elastic member may not be obtained due to the factors so that the superimposed feed of the subsequent sheet materials may be generated in the feeding operation.